Western Gull
Western Gull has collapsed: down 86% on the route-weighted index since 1970.
About the Western Gull
The Western Gull (Larus occidentalis) is a North American member of the Gulls, Terns & Skimmers (Laridae). In this analysis it is grouped with the wetland birds.
- Size
- 8.5–31.5 in long (22–80 cm) — a long-winged waterbird (typical for the family)
- Habitat
- Marshes, ponds, lakeshores and other freshwater wetlands.
- Diet
- Aquatic invertebrates, small fish, frogs and plant matter.
- Range
- Recorded on 30 Breeding Bird Survey routes across 3 states, most concentrated in the Northern Pacific Rainforest.
- Family
- Laridae · Wetland birds
Notable Western Gull Trends
Western Gull has collapsed in surveyed states: down 86% on the route-weighted index since 1970.
Western Gull Population Forecast
If the recent trend holds, Western Gull is projected to stay roughly flat through 2029, near 0.05 (95% range 0.00–0.27). A 5-year backtest shows a typical error of ±360.2%, with 100% of held-out values landing inside the 95% band.
| Year | Projected index | 95% low | 95% high |
|---|---|---|---|
| 2025 | 0.06 | 0.00 | 0.29 |
| 2026 | 0.06 | 0.00 | 0.28 |
| 2027 | 0.06 | 0.00 | 0.28 |
| 2028 | 0.05 | 0.00 | 0.28 |
| 2029 | 0.05 | 0.00 | 0.27 |
Where the Western Gull Is Detected
BBS routes recording Western Gull, sized by most recent count.
Western Gull Population Trend by State
| California | -84% | 1970 | 18 |
| Oregon | -98% | 1972 | 6 |
| Washington | -94% | 1971 | 6 |
Western Gull Population Trend by Region
Bird Conservation Regions are the ecological unit for trends.
| Northern Pacific Rainforest | -96% | 1970 | 19 |
| Coastal California | -72% | 1970 | 11 |
Western Gull Conservation Status
Our route-weighted index shows it down about 86% since 1970.
Source: USGS North American Breeding Bird Survey, retrieved 2026-05-22. Trend is a route-weighted relative-abundance index, not an absolute population.